The present invention refers to a machine housing at least one of the walls of which is provided on its outer side with ribs for the discharge of heat to the surrounding air. The housing is preferably that of a gear transmission. In known machine housings of this type the height of the ribs is generally equal to at least the thickness of the wall and frequently is even substantially greater than the thickness of the wall. In this way, it is attempted to obtain a paticularly large removal of heat. The rib pitch, i.e. the distance between ribs, is usually relatively small, since it is generally desired to have the largest possible number of ribs. One disadvantage of this known machine housing is its relatively great weight and danger of dirtying, impairing the removal of heat. Difficulties also arise upon the casting of such known machine housings.